|
|
|
I have a really sweet Volvo 7XX series turbo. Ever since I washed under the hood, the car intermittently runs really rough after the engine is hot. Today, just sitting in 95 degree sun for several hours, I drove it 5 miles home and I didn't think I'd make it up the road which has a slight grade to it! A mechanic I found came and got it, blew black smoke when he started it. He took it, changed spark plugs, drove fine for him, brought it home and I'm still having trouble with it. Did run better at first but now is just getting worse, especially after engine warms up.
Other problem I'm having is that the push button OD doesn't always result in the car shifting. Did clean under the button and that seemed to help a lot but button is still not as responsive as it should be.
Any ideas? especially on the running rough problem? Car has about 216,000 miles on it.
Thanks. Judy
|
|
-
|
|
|
UPDATE
I took my car, twice, to a shop where there is supposedly a mechanic who knows Volvos. First time, he changed out my fuel filter and the car ran really well for about 2 weeks. Then I drove it, hot day. Stopped, went in a store, came back out, and when I restarted car to come home, limped home all the way. Had to have towed to the shop.
2nd time: they say it was "flooded" which I don't understand how it got flooded given fuel injection, etc. and why I couldn't even start the car for day after day after day. So the repair receipt says they "cleared" that . In regard to the OD they said they checked it, removed OD shift solenoid and cleaned valve, replaced O rings.
I picked it up yesterday. Ran fine home until I stopped at the store, shut it off. When I restarted to come home, limped home all the way again.
They have never responded to my question about the ignition control module, whether that may be an issue or not; have not done any type of tune up on it; seem to really not know what's going on. I don't either. I need some better help! here guys. . . Problem getting worse, obviously, seems related to heat, driving, shutting off, and restarting at this point where before that did not cause the problem.
|
|
-
|
|
"They have never responded to my question about the ignition control module"
Who mentioned the "ignition control module"? I don't see it in this thread anywhere, but was going to mention it under it's slang name -- the Power Stage. It has a big transistor that gets hot from constantly switching the coil voltage on and off to generate high voltage needed produce sparks at the plugs. Because it runs hot, it is mounted on an aluminum plate the serves as a "heat sink", which is bolted to the left front inner fender.
To aid in transferring the heat away, the PS is mounted to it's heat sink on a thin layer of "thermal paste" or "heat sink compound". This stuff gets hard and brittle with age, losing much of it's heat transfer ability, which results in weaker spark voltage from the coil or even no spark in extreme cases. It's possible that your underhood washing may have dissolved or flushed away some/all of the old compound from your Power Stage.
Here's a Power Stage problem example from a brickboard search:
"I left the old bad power stage attached to the inside of the fender and connected the new part. I did not fasten it to anything, just tucked it under the negative battery cable to keep it from flopping around. The car engine started and ran fine without any connection to the body. I let the car idle in my driveway for 20 minutes and everything seemed OK. I then drove the car. After 5 minutes of driving, the engine was misfiring terribly. I pulled over and that new power stage was pretty warm. I reconnected the bad one to make it home."
Ask your mechanic to take the PS off and apply fresh heat sink compound. Or do it yourself if you can remove the 2 (Torx head?) screws holding it to the heatsink.
Here is a Google Search Result .
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
I had been thinking of that part as well and had asked the mechanic at least 2 if not 3 times to check it which never got done. Yesterday I took it apart, cleaned it up, ordered a new one, but just tinkering with old one seemed to help and I also cleaned all spark plugs which all had new black fouling on them.
So, if spark weak at the plug as a result, not all fuel would be burned in cylinders so the plugs would become fouled, right? which would not fire as well and then the mechanic would think I had flooded the engine, right? If I'm tracking things right here anyway.
What about the coil? Especially if I continue to experience issues. Can that be checked or should I just replace the darn thing??
Thanks so much.
Judy
|
|
-
|
|
|
Hi Judy,
Did your Power Stage "clean up" include fresh thermal paste? I really think the underhood washing is what started this debacle, and that thin layer of paste is what allows the PS to work properly for extended periods.
I also think your analysis of the weak spark theory and it's effect on the plugs, makes sense, and that gender bias probably played big part in your being ignored by the mechanic.
Coils do fail with age, but it takes ages. Personally I've never had a bad one in my life. There are (or were) places that could test coils, but I can offer no direct experience on the subject. If "porkface" chimes in, he'll probably say to look for an old back alley shop with a "Sun" brand tester.
But my money is still on the PS. It could just be getting old, but the coincidence of recent underhood washing (hosing maybe?) strongly suggests that the thin but critical thermal paste layer is all but gone, and the PS just can't take the heat any more (than a few minutes).
Even if you got a new PS, you would still need the thermal paste. And maybe that's all the old one needs. Your call, but if you do replace it, I'd suggest the Bosch version like you probably have now.
Press on,
Bruce
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
87 is a classic year for deteriorating engine wiring harness. Highly likely that this is your issue. Dave Barton used to sell good ones; some make new ones, or adapt other years which I believe is not that hard, but haven't done it.
OD, the push button is to take it out of OD. Problems can be in the switch, the wiring, or most often the solenoid on the trans. I have had 3 fail. You can get a good used one, or an adapter that bypasses it so you get OD but lose the ability to shift down to 3rd, for hills and towing. Many get by without it.
|
|
-
|
|
|
Thanks for your response, was afraid it might be something like that although visually the harness, etc., still looks ok. The other weird thing I noticed today, other than the limp home mode started after about only 5 miles, is that when I turn the headlights off, I could feel the car pick up a bit and it didn't limp quite so badly. (I usually drive with the headlights always on because turning off the car turns off the lights, safety thing and all).
As for the OD, I'm going to get the car into a repair shop sort of near me that has a Volvo mechanic working there and ask him to check the solenoid. I really use OD a lot, get better gas mileage with it. My cruise control has not worked for years.
Again thanks. I really appreciate Brick Board -- oh, one more question, yesterday when I was searching for answers, I ran across a post on BB about codes, how to interpret them, etc., and now I cannot find that post/page on the web. Do you know where I might look to find info on what the various codes mean on the '87 740 Turbo? (orig brought over from Sweden if that makes a difference)
|
|
-
|
|
|
Is this a stick or auto? If auto, overdrive is 'automatic', and the solenoid allows it to occur, it's not something you control in normal usage.
"s that when I turn the headlights off, I could feel the car pick up a bit and it didn't limp quite so badly."
This is telling, IMO. It sounds like the electrics, charging system, have issues. Maybe check the brushes on the alt, and go to a parts shop that has free testing and see what your alt is putting out, and condition of the battery.
|
|
-
|
|
|
Your year group has very limited diagnostic. It doesn't "throw codes". Just an idiot light blinking. Primitive
http://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm
--
Post Back. That's whats makes this forum work.
|
|
|
|
|
